Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred...
-
Upload
franklin-rodd -
Category
Documents
-
view
215 -
download
0
Transcript of Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred...
![Page 1: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/1.jpg)
Acetone and Hydroperoxyl Radical Equilibrium
Certainly Fascinating, But Is It Important To You?
Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura
Funding: NASA Upper Atmospheric Research Program NASA Senior Post-Doctoral Fellowship NASA Summer Faculty Research Fellow Program
![Page 2: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/2.jpg)
HO2/OH Atmospheric Chemistry
Importance to you?
Laboratory Study of and Atmospheric Observation of HOx Radicals
![Page 3: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/3.jpg)
For example: Photochemical Ozone Production
![Page 4: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/4.jpg)
Simplified Tropospheric Chemistry
Volatile Organic Compounds
Oxygenated Volatile Organic Compounds
![Page 5: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/5.jpg)
Understanding Atmospheric Chemistry
Overall Picture
![Page 6: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/6.jpg)
HO2 + Acetone HO2Acetone (CH3)2C(OH)OO?
Acetone in the Upper Atmosphere
• One of main OVOCs in the Upper Troposphere (UT)
• Key source of OH and HO2 (HOx) from photolysis
• Primary loss pathways in Upper Troposphere: Photolysis, Reaction with OH
• Recent experiments by Blitz, Orr-Ewing, Heard, Pilling suggest much lower photolysis yields at low T
An alternate oxidation pathway in the atmosphere? Possible Reaction with HO2?
• Hydrogen radicals in Upper Troposphere: HOx = OH, HO2
• In the atmosphere, [HO2] >> [OH]
• HO2 is known to react rapidly with formaldehyde at room temperature
Literature?
So, YES!!! Determination of Acetone/Hydroperoxyl Radical Equilibrium IS Important to YOU!
![Page 7: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/7.jpg)
Int. J. Chem. Kinet. 32, 573 (2000).
![Page 8: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/8.jpg)
ADDUCT
PEROXY RADICAL HO(iPr)OO
REACTANTS
COMPUTED STATIONARY POINTSB3LYP/cc-pVTZ GeometriesG2Mc/DFT Energies
HO2 + Acetone HO2Acetone
(CH3)2C(OH)OO?
MOLECULAR COMPLEX
![Page 9: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/9.jpg)
Atmospheric Loss Process
1. HO2 + Acetone are in equilibrium with peroxy (H-bonded molecular complex is pre-equilibrium config)
HO2 + CH3C(O)CH3 → HOC(CH3)2OO
k(200K) = 6.9 10-12 cm3 s-1 Kc(210K) = 6.0 10-13 cm3
2. Peroxy radical reacts with HO2 or NO, leading to loss of HO2
(then important to include in HO2 / OH budget)
3. Acetone sink: If Herman’s et al. calculation correct,
HO2 removal on par with photolysis & greater than from OH
![Page 10: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/10.jpg)
Abstraction
Addition
Higher Barrier – NO REACTION!
![Page 11: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/11.jpg)
Does this rxn occur at relevant atmospheric T?
Kc(T)
2.27E-172.32E-151.17E-133.05E-12
k+
4.50E-131.06E-122.20E-124.04E-12
k-
1.98E+044.58E+021.89E+011.33E+00
How?? Experimental Determination via
Infrared Kinetics Spectroscopy (IRKS)
HO2 + CH3C(O)CH3 ⇌ HOC(CH3)2OOk+
k-
Because k- is so large, Keq is the quantity that determines effective rate of removal
![Page 12: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/12.jpg)
Excimer laser308 nm
D2 lamp
diode laser
detector
low pass filter
monochromator
computer
6.8 MHz current modulator
2x/phase shifter
demodulated signal
FM signal
gas entranceexit exit
Herriott cellPD
Infrared Kinetic Spectroscopy Apparatus
UV
NIR{2ν(OH)}
T-controlled FLOW CELL
λ = 220 nm (near HO2 max)
Cl2 + hν → 2 ClCl + CH3OH → CH2OH + HClCH2OH + O2 → HO2 + CH2O
![Page 13: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/13.jpg)
Herriot Cell Mirror
![Page 14: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/14.jpg)
FM Detection of HO2 NIR Lines by Diode Laser
InGaAs/InP single-mode DFB Diode Lasers
1.4 and 1.5 m fabricated at JPL,
Selectivity for HO2
Detection of single rotational lines
Wavelength Modulation
2f detection at 7 MHz modulation
Near shot-noise limited detection
Herriott Cell
30 passes, Leff = 2000 cm
Sensitivity (Minimum detectable absorption)
5x107 Hz or 2. 5x1010 cm1HzHO2 Detection Limit (6636 cm1, 295K, 100 Torr):
1.0 x 10 cm3 1 Hz
3 x 10 cm 10kHz, 1 shot
HO2 line
6625.80 cm-1
-1.0
-0.5
0.0
0.5
1.0
1.5
-40 -30 -20 -10 0 10 20 30 40
Relative Frequency (milli-cm-1)
HO2
Sig
nal
(micr
ovol
t)
![Page 15: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/15.jpg)
Association Reaction
HO2 + (CH3)2CO ⇄ (CH3)2CO---HO2
isomerization ↓ (CH3)2COH ← (CH3)2CO---H †
O▬O O▬O
MOLECULARCOMPLEX
2-hydroxyisopropylperoxy (2-HIPP)
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
1086420ms
IR05t [Ace] = 0 IR06t 2.24e15 IR09t 2.98e15 IR10t 3.50e15 IR13t 4.52e15 IR14t 5.62e15
HO2 NIR Decay Curves at Varying [Acetone]
T = 221 K T = 297 K
0.12
0.10
0.08
0.06
0.04
0.02
0.00
3020100ms
IR02t [Ace] = 0.0e15 IR03t 2.18 IR04t 4.06 IR05t 5.48 IR06t 5.41 IR07t 7.09 IR08t 9.93 IR09t 12.8 IR10t 17.5 IR11t 20.5
Time (msec)Time (msec)
HO
2 A
bso
rban
ce
Dramatic decreasein [HO2] at lower T& same [Acetone]
Measuring [HO2] decay upon adding Acetone
Does not occur at room T, but may at lower T
Measure with increasing [Acetone]
Preliminary Result:
No HO2 + Acetone rxn !!! Must consider all chemistry Cl + Acetone HCl + CH3C(O)CH2
Decreases HO2 made Slows at Low T {k(297) = 2.1E-12 ; k(221) = 1.0E-12)}
Interpretation: 1) Complexation occurs at lower T 2) Equilibrium reached quickly followed by HO2 rxns
![Page 16: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/16.jpg)
Fitting Rise and Fall of Short time decay not possible
Method Developed:
• Fit Longer time decay with simple HO2 self-reaction
• Determine [HO2] at time = 0, w/out & w/ [Acetone]
• Correct for Cl + Acetone reaction
• Determine Keq from equilibrium concentrations
• Repeat for several [Acetone] at several T
• Keq(T) ΔrH & ΔrS
First must determine Cl + Acetone reaction at T=298K
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
1086420ms
IR05t [Ace] = 0 IR06t 2.24e15 IR09t 2.98e15 IR10t 3.50e15 IR13t 4.52e15 IR14t 5.62e15
![Page 17: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/17.jpg)
0.12
0.10
0.08
0.06
0.04
0.02
0.00
3020100ms
IR02t [Ace] = 0.0e15 IR03t 2.18 IR04t 4.06 IR05t 5.48 IR06t 5.41 IR07t 7.09 IR08t 9.93 IR09t 12.8 IR10t 17.5 IR11t 20.5
80
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
210
-1-2
x10-3
0.10
0.08
0.06
0.04
0.02
0.00
IR s
igna
l/ (V
)
1086420ms
3210
-1-2
x10
-3
0.10
0.08
0.06
0.04
0.02
0.00
IR s
igna
l/ (V
)
1086420ms
3210
-1-2
x10-3
80
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
210
-1
x10-3
80
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
210
-1-2
x10-3
80
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
2
1
0
-1
x10-3
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
3210
-1-2
x10-3
70
60
50
40
30
20
10
0
IR s
igna
l/ (V
x10
-3 )
1086420ms
2
0
-2
x10-3
Cl + CH3C(O)CH3 → HCl + CH3C(O)CH2 (~10 sec)
O2 + CH3C(O)CH2 → CH3C(O)CH2OO (fast excess O2)
HO2 + CH3C(O)CH2OO → Products (k12f)
HO2 + HO2 → H2O2 + O2 (k1f)
Fit with literature k12f and k1f from [Acetone] = 0 fit
Agree w/ lit. (no HO2 + Acetone reaction at Room T)
T =297 K
Fits of Cl chemistry with Acetone & O2
![Page 18: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/18.jpg)
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
IR s
ign
al/ (
V )
3.53.02.52.01.51.00.50.0ms
43210
-1-2
x1
0-3
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
IR s
ign
al/ (
V )
3.02.52.01.51.00.50.0ms
3210
-1-2
x1
0-3
80
60
40
20
0
IR s
ign
al/ (
V x
10
-3 )
3.53.02.52.01.51.00.50.0ms
210
-1
x1
0-3
80
60
40
20
0
IR s
ign
al/ (
V x
10
-3 )
3.53.02.52.01.51.00.50.0ms
1.0
0.0
-1.0
x1
0-3
80
60
40
20
0
IR s
ign
al/ (
V x
10
-3 )
3.02.52.01.51.00.50.0ms
1.00.50.0
-0.5-1.0
x1
0-3
60
40
20
0
IR s
ign
al/ (
V x
10
-3 )
3.53.02.52.01.51.00.50.0ms
1.0
0.0
-1.0
x1
0-3
Preliminary objective: Determine thermodynamics
Family of NIR HO2 decay curves at T = 221Kat varying acetone concentrations
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
0.00
1086420ms
IR05t [Ace] = 0 IR06t 2.24e15 IR09t 2.98e15 IR10t 3.50e15 IR13t 4.52e15 IR14t 5.62e15
Cannot Fit Curves with Cl reactions
![Page 19: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/19.jpg)
Initial analysis: find [HO2]o([Ace]) at t = 0 s to determine equilibrium concentration prior to
subsequent kinetics
60
40
20
0
IR s
igna
l/ (V
x10
-3 )
3.53.02.52.01.51.00.50.0ms
1.0
0.0
-1.0
x10
-3 1) [HO2]o(0) determined from fit &
corrected for Cl rxn with Acetone
2) [HO2]eq = [HO2]o([Ace]) determined from fit
3) [Complex] = [HO2]o(0) – [HO2]o([Ace])
[Complex]
Keq =
[Ace] [HO2]o([Ace])
(excess)
Measure Keq at several atmospherically relevant temperatures
![Page 20: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/20.jpg)
T(K) (2 Kc(cm3/molec) (pph)
215.6 2.957E-16 12.7
220.7 1.506E-16 6.9
222.5 1.227E-16 9.9
226.8 9.087E-17 13.7
227.6 7.856E-17 17.3
231.9 7.177E-17 22.5
232.3 5.977E-17 9.5
237.1 3.955E-17 5.8
242.7 2.589E-17 12.6
243.5 2.451E-17 17.4
245.9 2.961E-17 1.6
249.6 2.898E-17 5.2
254.5 1.335E-17 16.9
266.2 1.408E-17 23.7
272.3 7.671E-18 18.3
Kc(T) (cm3 molec-1) Van’t Hoff Plot: Rln(Kp) vs. 1/T slope = -ΔrH°; intercept = ΔrS°
ΔrH° = -31 1.7 kJ/mol
ΔrS° = -70 7.2 J/mol/K
ΔrG° = ΔrH° - T ΔrS°
Keq(T) = exp (- ΔrG° /RT)
Van't Hoff Plot (not weighted)
y = 30.97x - 0.0700
R2 = 0.9614
0.040
0.045
0.050
0.055
0.060
0.065
0.070
0.075
0.080
0.00360 0.00380 0.00400 0.00420 0.00440 0.00460
1/T(K-1)
Rln
Kp
![Page 21: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/21.jpg)
Comparison of Equilibrium ConstantsKc, cm3 molec-1
![Page 22: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/22.jpg)
More ComparisonsReaction Thermodynamics Compared to Calculated Values
Aloisio product:
Like complex!!!
![Page 23: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/23.jpg)
Reaction to Complex
HO2 + (CH3)2CO ⇄ (CH3)2CO---HO2
↓ (CH3)2CO---H †
O▬O
MOLECULARCOMPLEX
Herman et al.
Cours et al.
Aloisio et al.
Both Planar
Perpendicular
Calculations
![Page 24: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/24.jpg)
Comparison with Methanol and Water
Source ΔrHo (kJ/mol) Do (kJ/mol)
HO2 + Acetone(This Work)
-31
HO2 + Methanol(Christiensen et al., 2006)
-36.8
H2O + H2O(Curtiss et al., 1979)
-15.0
HO2Acetone(Aloisio et al., 2000)
37.3
HO2Methanol(Christiensen et al., 2006)
35.7
H2OH2O(Klopper et al., 1995)
21.0
![Page 25: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/25.jpg)
Atmospheric Implications(Just a taste.)
Analysis by Hermans et al.: Acetone removal (keff) from UT Keq
At 190 K, keff = 5 x 10-6 s-1 which is greater than acetone photolysis (4 x 10-7 s-1)
However, if our results are correct and 2-HIPP is product: Keq = 1.9 x 10-15
compared to Hermans et al. Keq = 2.0 x 10-11
keff = 4.3 x 10-10 s-1
![Page 26: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/26.jpg)
Summary
• Discovered reaction between HO2 + Acetone
• Developed Method to Determine Keq for HO2/Carbonyl Reactions
• Able to Measure Keq Over Wide Temperature Range Including Atmospherically Relevant Temperatures
• Thermodynamic Parameters Determined: Possible Clues to Reaction Product and Its Structure
• Will Be Able to Determine Its Impact on the Atmosphere
![Page 27: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/27.jpg)
Future Work
1) Search for products (acetonylperoxy, 2-HIPP, Molecular Complex)
We have done some of this: T = 297 K acetonylperoxy: CH3C(O)CH2OO
12
10
8
6
4
2
0
-2
-4
x10
-3
2520151050ms
12
10
8
6
4
2
0
-2
-4
x10
-3
2520151050ms
σ(cm2/molec) at λuv = 280 nm
2.07E-18 acetonylperoxy
0 HO2
2.00E-20 H2O2
[Ace] = 0 [Ace] = 2.05E16
For (CH3)2C(OH)OO and (CH3)2C(O)OOH
No spectrum observed in uv; Calculations underway to estimate OH stretching frequency and A-X transition
2) Measure forward rate constant
Very difficult work; has been accomplished for HO2 + methanol
3) Apply this method to many HO2 / Carbonyl systems: MEK, Acetaldehyde, Formaldehyde
![Page 28: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/28.jpg)
Acknowledgements
HarryKroto
AaronNoell
StanSander
MitchioOkumura
![Page 29: Acetone and Hydroperoxyl Radical Equilibrium Certainly Fascinating, But Is It Important To You? Fred Grieman, Aaron Noell, Stan Sander, Mitchio Okumura.](https://reader038.fdocuments.net/reader038/viewer/2022110304/5519cff55503468b0c8b4782/html5/thumbnails/29.jpg)
The research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology under contract to the National Aeronautics and Space Administration
*This research was supported by an appointment of Fred Grieman to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Oak Ridge Associated Universities through a contract with NASA.
The Future
KiraWatson
Casey Davis-Van Atta
AileenHui
1st yr.Caltech
GradStudent(not shown)
PomonaChem Majors